The present invention relates generally to electroluminescent lighting technology and, more particularly, to a display on which electroluminescent lamps with coplanar printed contact pads electrically connect the lamp with a continuous bus bar at any point along the length of the bus bar.
Electroluminescent (EL) lighting technology provides a desirable source of illumination for several reasons. First, EL lamps emit a coherent light having a relatively low level of glare when compared to incandescent lamps, fluorescent lamps or other lamps using conventional lighting technologies. Second, EL lamps operate on a relatively low level of power when compared to lamps incorporating the aforementioned lighting technologies, and thus are less expensive to operate. Third, EL lamps have thickness profiles typically of only a few thousandths of an inch, thus permitting these lamps to be used in applications where lamps having thicker profiles could not be used. Fourth, due to the recent advancements in EL lighting technology, EL lamps exhibit longevity of operational life and thus need not be replaced as often as lamps incorporating conventional lighting technologies.
The extended operational life of conventional EL lamps mentioned above has been primarily due to the microencapsulation of phosphor particles to emit light. The microencapsulation of the phosphor particles protects the particles from moisture that, if allowed to penetrate the EL lamp protective barrier and contact the phosphor particles, would diminish the ability of the particles to emit light. One traditional method of protecting the phosphor particles from moisture ingress is to laminate the particles between two sheets of polychlortrifloroethylene (PCTFE). By sealing the phosphor particles between the PCTFE sheets, the ability of moisture to penetrate through to the phosphor particles is greatly reduced.
However, the above mentioned lamination process suffers from two major drawbacks. First, in order to effectively prevent moisture ingress, the laminated PCTFE sheets must maintain a seal around the periphery of the sheets in order to remain effective. This seal, however, often deteriorates over a period of time and when exposed to repeated frictional forces or other similar adverse conditions. Second, the EL lamp construction requires that electrical connection points be established with the lamp through wires, connector pins, or contact pads. Such electrical connections require that the PCTFE sheets be punctured or the seal between the sheets be compromised in order to make the electrical connections. Both such situations compromise the water tight seal and typically lead to decreased lamp life and lighting effectiveness.
The above mentioned drawbacks associated with EL lamination techniques have been largely eliminated through the use of a screen printing process utilizing microencapsulated phosphors in forming screen printed EL lamps. By forming EL lamps through this screen printing process, wires, crimp pins and contact printed pads are implemented without puncturing, piercing or otherwise compromising the moisture barrier encapsulating the phosphor particles.
While the above described lamination process has eliminated many of the drawbacks associated with the EL lamp lamination process, areas remain within the art where technological advancement would be desirable. For example, with conventional EL lamps manufactured through the above described screen printing process, typically the wires, crimp pins or contact pads connecting the encapsulated lamp with the power source require that the graphic be snap fit or correctly aligned with power source sockets or receptacles in order to illuminate the associated lamp graphics. Thus, the EL lamps may only be connected in display areas in which the power source sockets or receptacles are located, thereby limiting flexibility in lamp arrangement. In addition, to achieve alternate lighting configurations, i.e., a continuous lighted sequence, a flashing lighted sequence or a running lighted sequence, circuitry associated with the power source must typically be altered or switched.
Therefore, a need exists for an EL lamp, and associated method for manufacturing the same, that may be located at any point along a continuous conducting surface such as a bus bar. There also exists a need for an EL lamp which allows a person installing the lamp to control the lighting characteristics of the lamp through selective placement of the lamp without having to switch or otherwise alter the power supply or associated circuitry. Further, there exists a need for an EL lamp having electrical contact pads that prevent shorting of the EL system display if the lamp is misaligned during insertion into the display. In addition, there exists a need for a method of forming an EL lamp in which electrical contact pads are formed coplanar to one another to allow the associated EL graphics to be manipulated as described above.